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Classic Mercedes Benz diagnostics, consultations, inspections
This page is dedicated to one major problem S-class, SL class, E-class, and some C-class Mercedes vehicles from ‘90s suffer from - leaking A/C evaporator.
Many owners of fine Mercedes automobile drive with open windows not because they want to enjoy 100 degree summer air or make other drivers think that they have extremely freezing A/C . Most likely A/C has no refrigerant due to the leaking evaporator core. If evaporator has a leak putting freon for A/C to work for a few days doesn’t make sense. It’s expensive and in many cases doesn’t last long. In some cases, the leak can be elsewhere, but if A/C evaporator has a leak that is one major job to replace it.
When I bought 1990 300E A/C system had no refrigerant in it. I bought the car the end of winter and drove it for few months until one warm rainy day I got stuck in traffic during heavy rain. My windows fogged up and I had to put on the heat to defrost windows. When the outside temperature is 90 degrees and one sits in closed car with heater on, well it’s definitely not cool. I was oven-baked Victor at that moment. I charged A/C system and surely it leaked out in the week. Evaporator core was leaking. In evaporator drains I found green dye indicating the leak. Not to be stuck with having heat on in summer to defrost my windows I started removing the dashboard to get to evaporator housing. Once the housing was removed I also replaced a couple of vacuum actuators as some air ducts did not work properly. Replaced evaporator and went to the A/C shop to charge the system (R12 gas is not available at auto parts stores) and lived happily through summer.
When I bought my 1992 500SEL I had to remove A/C condenser and radiator to perform an engine repair. The previous owner replaced A/C compressor and I was anxious to recharge A/C system and get frozen by great A/C performance. I was happy for 2 weeks. One very hot day I noted A/C is not as cold as it was. After inspection and testing same green dye was found under the car indicating leaking evaporator. I thought E-class evaporator replacement was big and time consuming job but S-class evaporator was big and time consuming job in the 3rd degree. I then understood why evaporator replacement is so expensive. It took me 4 days to replace my S-class evaporator under the blazing summer sun but was well worth it. I had evaporator to cool all the way down to 32F (according to climate control diagnostic readout pressing and holding AUTO button for 5 seconds). Since then I have replaced many more evaporators on other cars due to leaks
I heard stories that people paid over $4000 at the dealer to replace leaking evaporator on S-class. Very few general repair shops will agree to do the job as they have very limited experience working on S-class. Many shops don’t want mechanics busy with one car for 3-4 days. It is one big and delicate job.
Since I have replaced many evaporators on E-class and S-class I know all clips and hidden bolts and remove panels without damages. Gloves used at all times not to stain any interior trim. Progress is recorded. Final video is recorded with system pressures and temperatures after the job is done. Care and attention to details are very important to me. This is one big job and it needs to be done right the first time.
Below are some pictures showing some progress
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